The therapeutic use of plant-derived compounds, synthetics analogues, or plant extracts are gaining new attention as alternative treatments for infections, stress, and other health problems as well as promoting physical and psychological well-being.
It has been suggested that breathing in fragrant air stimulates the odor-sensing nerves in the nose sending impulses to the limbic system of the brain or activating hormones or enzymes in the blood that stimulate the adrenal glands.
More than 100 plants are thought to have beneficial effects when used as either whole leaf or as oils or resins. Common plants include flowers (rose, narcissus), roots (orris), leaves and needles (eucalyptus, pine), resins (turpentine), seeds (caraway), fruits (lemon, lime), berries (cloves), bark (cinnamon) and wood (cedar), spices (basil, anise, nutmeg, cumin, oregano), substances related to plant-based or synthetic medicine (marijuana, tobacco, St. John's wort).
When heated to certain temperatures, these compounds are converted into gaseous form, producing a micro-fine mist containing the beneficial molecules, which can then be inhaled, either directly as a concentrated dose or in a diffused form by expelling the gaseous vapor into the air of the surrounding environment.
Those preferring a concentrated dose will often smoke the compounds, as is seen with cigarettes or marijuana.
However, smoking these compounds subjects them to extremely high temperatures, causing a combustion reaction, creating toxic byproducts that can lead to a multiple of diseases such as lung cancer, asthma and chronic bronchitis.
Combustion is an exothermic reaction causing the compounds to undergo oxidation.
In some cases, the temperatures are high enough to cause a pyrolysis reaction, wherein the compounds undergo a thermochemical decomposition, breaking the chemical bonds between carbon atoms, releasing large amounts of volatile and semi-volatile smoke constituents.1 1Norman, A. (1999). Smoke Chemistry. In: D. Layten Davis & Mark T. Nielsen. Eds. Tobacco Production, Chemistry and Technology, Oxford; Blackweil Science Ltd.
A major group of compounds formed during pyrolysis is that of the polynuclear aromatic hydrocarbons. Ethylene glycol is pyrolytically converted to the human carcinogen ethylene oxide2. 2IARC (1994a) Ethylene oxide. In: Some industrial chemicals. Lyon, International Agency for Research on Cancer, pp 73-159 (IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 60).
According to the National Institute of Health, studies suggest that “the chemical constituents in tobacco smoke that present health concerns increased as the temperature increased from 300° C. to 1,000° C., but some compounds (e.g., acrolein and formaldehyde) reached their maximum yield at 500° C. and the yield remained approximately the same at higher temperatures.3 3Centers for Disease Control and Prevention (US); National Center for Chronic Disease Prevention and Health Promotion (US); Office on Smoking and Health (US). Atlanta (Ga.): Centers for Disease Control and Prevention (US); 2010.
For example, the temperature of cigarette coal can range from a resting (smoldering) temperature of around 600° C. to peak puff temperatures exceeding 900° C. during a 35 mL, 2-sec puff (the pyrolysis/distillation zone).
More than 5,000 smoke constituents have been identified in cigarette smoke, with about 150 identified as smoke toxicants.4 4Rodgman, A., Perfetti, T. A. (2008). The chemical components of tobacco and tobacco smoke. USA: Taylor and Francis Ltd.
However, it is well known in the industry that heating plant materials or other synthetic medicinal products at lower temperatures, a technique known as vaporization, releases beneficial organic compounds.
Plant products, for example, vaporize at much lower temperatures than are seen during combustion or pyrolytic reaction, as shown in in the list below.                Chamomile—Vaporization temperature: 374° F./190° C.        Passion Flower—Vaporization temperature: 309° F./154° C.        Green Tea—Vaporization temperature: 374° F./190° C.        Peppermint—Vaporization temperature: 331° F./166° C.        Eucalyptus—Vaporization temperature: 266° F./130° C.        St. John's Wort—Vaporization temperature: 302° F./150° C.        Cannabis—Vaporization temperature: 356-410° F./180-210° C.        Tobacco—Vaporization temperature: 257-302° F./125-150° C.        
As shown, some temperatures are displayed in ranges due to multiple constituents within the plant compounds, each having unique vaporization temperatures.
However, while vaporization profiles are equivalent for constituents across various forms, combustion points may vary.
For example, cannabinoid concentrates, such as resins or waxes, are very lipid soluble, but water insoluble, resulting a very viscous substance. Cannabinoid concentrates resemble a thick, sticky, gummy resin and are less likely to combust than the dry flower or leaf forms.
Additionally, concentrates are typically more potent than non-concentrates.
THC concentrations for cannabis resin is typically 5-10%, rarely exceeding 12% whereas dry cannabis normally contains 3-4% THC. The THC content of hash oil is much more variable with levels ranging from 15% to over 60%.5 5L. A. King, Drug content of powders and other illicit preparations in the UK. Forensic Science International 85 p. 144 (1997) 135-147.
However, it is the safety profile of vaporization over combustion methods that have made vaporization of organic and synthetic compounds for inhalation so popular.
A recent study on the vaporization of cannabis stated that its major finding was a drastic quantitative reduction in non-cannabinoid compounds in the vapor strongly suggesting that vaporization is an effective method for delivering medically active cannabinoids while effectively suppressing other potentially deleterious compounds that are a byproduct of combustion.6 6Gieringer D, Laurent S J, Goodrich S. Cannabis Vaporizer Combines Efficient Delivery of THC with Effective Suppression of Pyrolytic Compounds. Journal of Cannabis Therapeutics. 4:7-27.
This view was expressed by the Institute of Medicine in its report on medical marijuana (IOM 1999, Executive Summary p. 8): “Because of the health risks associated with smoking, smoked marijuana should generally not be recommended for long-term use . . . . The goal of clinical trials of smoked marijuana would not be to develop marijuana as a licensed drug, but rather as a first step towards the possible development of non-smoked, rapid-onset delivery systems.”7 7Id.
The safety profile of vaporization has thus paved the way for a host of vaporizing apparatuses, the most popular being e-cigarettes.
The majority of e-cigarette apparatus' resemble traditional cigarettes, but instead of tobacco, the e-cigarette uses a cartridge filled with a nicotine infused liquid, which is heated by a battery powered coil.
The resulting vapor is released into a chamber where it can be inhaled, much like a traditional cigarette.
The aerosol produced has a simpler more predictable composition and maintains the general smoking experience.
However, the heating element in an e-cigarette does not produce temperatures required to vaporize many plant-based or synthetic materials.
For example, marijuana vaporization requires a temperature range between 180-210° C. to release the beneficial Cannabinoids and Terpenes within the plant.
Cannabis contains sixty-six cannabinoids, the most well known being delta-9-tetrahydrocannabinol (Δ9-THC), which is the main psychoactive ingredient in cannabis.
As well, Cannabis has over 120 terpenes responsible for producing various fragrances, such as floral, citrus, woodsy, and plant-based or synthetic.
Cannabinoids are highly combustible and many of the delicate terpenes responsible for the fragrances are easily destroyed in a combustion reaction.
With vaporization, more than twice as many cannabinoids and terpenes are delivered to the user than one would get from smoking.
Gas chromatograph mass spectrometer (GCMS) examining the gas components resulting from vaporization showed that the vapor was remarkably clean, consisting 95% of THC, the principal psychoactive constituent of cannabis, with the remaining 5% consisting of terpenes and other cannabinoid related substances.
In contrast, over 111 different components appeared in the gas of the combusted smoke, with non-cannabinoids accounting for as much as 88% of the total gas content of the smoke.8 8Norman, A. (1999). Smoke Chemistry.
Examples of vaporizers on the market today are the Pinnacle Pro Vaporizer by VaporBlunt and the Volcano Digit, by Storz and Bickel, which both use a coil type heating element.
The Pinnacle Pro is a handheld vaporizer that looks similar to an e-cigarette. The unit is approximately five inches long, an inch in diameter and weighs about 100 grams. The vaporization material is placed at one end of the pipe, along with cartridges for flower or hash oil.
The unit heats the vaporization material by activating the heating element, which heats a conductive substance that is in direct contact with the vaporization material. The heating element is only one inch from the mouthpiece, which can make the vapor hot enough to irritate or burn the throat, depending upon which material is being vaporized; a common safety concern of current portable vaporizers. To compensate, the unit can be used in conjunction with a water pipe, which can reduce the heat of the vapor. Another downside of current Vaporizer technology is the start-up time.
The Pinnacle Pro takes almost one minute to heat up before a user can inhale the vapor. Also, its significant power requirements allow for only about an hour of usage before the unit needs to be recharged. The power and heat generation needs often lead to a shortened shelf life.
One of the most popular Vaporizers is the Volcano Digit, which is a cone shaped tabletop unit measuring approximately 7.9 inches at it base and 7.21 inches high, weighing 4.0 pounds. The Volcano uses a conduction method, albeit a larger one.
The advantage of the larger units is a larger conduction plate, plate temperature accuracy, and a larger chamber to hold the vaporization material.
However, they are not portable, and the process is relatively complex and time consuming verse that of e-cigarettes. For the Volcano, a user adds the vaporizable contents into the heating chamber.
The Volcano unit is turned on and a temperature chosen via a digital readout. It takes approximately four minutes to reach vaporization temperature. The user must then attach a vapor balloon to the top of the heating chamber.
Over the course of about 30 seconds, a plastic balloon connected to the device fills up with vapor. The user attaches a mouthpiece to the balloon from which the vapor inside can be inhaled.
While current Vaporizers may function satisfactorily under certain circumstances, there is a need for an improved portable Vaporizer that can be used to smoke plant based materials, with short startup times, low power consumption, long battery life, flexible temperature control, and enhanced safety, without the risk of metal “off gassing” of toxic vapors.